Sunday, 26 April 2015

Comparing antibiotic effectiveness

Different antibiotics work in many different ways to kill bacteria, but not all antibiotics work on all bacteria.


Poured plates containing different bacteria types (1 type per plate)
Solutions of different antibiotics
Filter paper discs


Number the disks with a pencil.
Soak discs numbered 1 in the first solution, 2 in the next etc.
Place a disc numbered 1 on the agar in each plate.
Repeat with the other discs.
Place the lids on the dishes, tape down in 4 places. Do not open the plates again.

Incubate for up to a week to allow the bacteria colonies to reproduce and become visible.

Measure the distance from the edge of each disc to the nearest bacteria colony.

Compare the data to see which antibiotic affects which bacteria type the most.


All equipment should be kept sterile. Wash your hands before and after using an antibacterial hand wash - gloves may also be worn. Plates will need to be autoclaved once they have been examined.